Presents on DG

8/10/2019 Presents on DG

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DG SET

Diesel generator sets are acombination of engine andalternator, which convertschemical (Fuel) energy into

electrical energy.


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DIESEL ENGINES

Diesel engines converts

chemical (Fuel) energy intomechanical energy.

These are CompressionIgnition (CI) Engines.

Clean Air is compressed andthe fuel is then injected inatomized form at the correcttiming.


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MAJOR COMPONENTS

CYLINDER BLOCK

It houses the pistons andliners and should be stronger

enough to withstand pressure

developed inside combustionchamber.


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CYLINDER HEAD

It houses the inlet and exhaust valves

and their operating systems. The all thejoints should be leak proof at valve

insertfillings.


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CYLINDER LINERS

These are fitted inside the cylinder

block.The piston moves inside the liner.

Water cooling is provided for cooling

these.


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CAM SHAFT

Cam shafts have lobes to operate

the different valves at different settimings.


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VALVES

There are different inlet and exhaust valves

for taking the fresh air and escaping the

exhaust gases.


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PISTON

It moves up and down in side combustion

chamber.

It is connected to the crank shaft.

Pistons in each cylinder with the piston rings

should be able to handle the peak cylinder

pressure with minimum power loss.


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PISTONPIN

It connects the connectingrod to the piston.


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FUEL PUMP

Engine driven fuel pump is

provided to ensure

sufficient flow and pressure

of fuel inlet to the engine

from the day fuel tank


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FUEL INJECTORS

It supplies the fuel in the combustion

chamber in an atomized form to

ensure proper, fast and complete

combustion.


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WATER RADIATOR

It stores water for circulating in thesystem for cooling the various partsof the engine where heat is beingdeveloped.


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THERMOSTAT

It is meant to control the

temperature of coolant .

It helps engine gain the operatingtemperature quickly by not

allowing the coolant to pass

through radiator but making it tocirculate through the system.


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FLYWHEEL

The engine shall be fitted with a

heavy, dynamically balanced

flywheel suitable for constant speedgenerator duty to meet cyclic

variations as per the requirements

of BS 649.


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SPEED GOVERNOR

An efficient, approved, engine

speed governor maintain enginespeed at all conditions of load in

line with the requirements of BS

5514 and this specification.


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CONNECTING RODThe connecting rod is heavy duty

and made of forged special steelsuitable for handling power transferfrom the piston and combustion

chamber to the crankshaft.The connecting rod piston

crankshaft assembly shall ensureefficient and smooth transfer ofpower with minimum wear and tear.

Forced lubrication as required isensured.


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TURBOCHARGER

It is meant to supply sufficient air into

the combustion chamber under

pressure.

It is driven by exhaust gases.

The ultimate purpose of turbo charger

is to increase the engine power with

same size of engine.


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GOVERNOR

The range of manual adjustment shallnot be less than 5% of rated speed.

The governor control should beisochronous type and thus maintain

constant speed of the engine at differentload up to the maximum rating of theengine.

The governor shall be suitable forisochronous paralleling and load sharingwith another generator.


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AFTER COOLER

The compressed air from the turbocharger shall beafter-cooled with water to air heat exchanger as in-built engine component for efficient operations.

The outlet compressed air temperature from the after-

cooler shall preferably be monitored for control of fuelinjection system. This is to enhance engineperformance level and avoid pre-mature requirementsof maintenance.

The density of air is increased by cooling air.


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STARTER MOTOR

The starting system is suitable for

three successive start attempts with

time intervals between attempts.

In case of failure of the three start

attempts, a failed-to-start alarm shall

be energised and the engine shall be

stopped for a pre-determined time forfurther starting attempts.


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DIFFERENT STROKES OF

ENGINES

Induction Stroke

Compression Stroke

Power Stroke

Exhaust Stroke


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INDUCTION STROKE

In this stroke the piston moves from

TDC to BDC.

Inlet valves remain opened.

Exhaust valve remain closed.

Air under force enters the combustion

chamber through turbocharger.


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COMPRESSION STROKE

In this stroke piston moves from BDC

to TDC.

Inlet and Exhaust valves are closed.

The air inside combustion chamber is

compressed.

The temperature and pressure of the

air start rising as the piston moves

from BDC to TDC.


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ENGINE SYSTEMS

AIR SYSTEM

LUBRICATION SYSTEM

COOLING SYSTEM

FUEL SYSTEM

EXHAUST SYSTEM


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LUBRICATION SYSTEM

The main components of lubrication

system are

Oil Filters

Oil Sump

Oil Pump

Oil Coolers


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The flow and pressure is developed by

engine driven lubricating oil pump and is

sufficient to ensure required flow andpressure of oil to all required points.

Engine lubrication is a closed circuit wet

sump, forced feed system supplied by anengine driven pump through gear-train

arrangement and fitted with pressure

regulating and relief valves, sump suctionfilter and changeover renewable full-flow

line filters.


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The oil system is used to

provide Lubrication to moving parts

Removing the heat from

system, Forming a film on the piston

to avoid corrosion and also

To clean the system


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At normal speed and loads the oil

pressure of engine should be between50-70 psi depending upon condition

and load on engine.

The special lub oil is recommended to

be used in Cummins engines with

additives to increase the engine life.

Th il d d


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The oil should be changed onrunning hours or period basiswhich ever falls early.

The lub oil capacity is nearly 177litres.

The oils recommended are

Valvoline power supreme SAE-15W

40 or any 15 W-40 multi grade oilmeeting the CF-4 OR CH -4, API

categories.

FUEL SYSTEM


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FUEL SYSTEM

The fuel system is to :

To supply the clean fuel to the system.

To control the quantity of fuel to

cylinder.

To inject the fuel in atomized form.

To ensure the correct timing of fuel

injection.To govern the engine speed at various

loads.

Th i t f f l


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The main components of fuel

system are

Fuel Tank.

Fuel filters.

Magnetic filters.

Fuel pump.

Electrical shut down valve.

Governor.

Injector.

The injectors used in K-Series engines are


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The injectors used in K Series engines areSTC injectors with less drain flow

STC - Step Timing Control

STC allows the engine to operate inadvance timing while starting and lightload conditions and at normal timingduring high and medium engine loads.

STC during advance timings gives : Reduced cold weather while start.

Improved light load fuel economy.

Reduced injector carbonizing.STC during normal timing :

Controls cylinder pressure.

Reduced emission.


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Magnetic filters is used after the fuel pump

to avert any metallic parts, which can

damage the engine. Fuel injection control is with electronic

actuators with fuel injection timing control

mechanism, which is fast acting torespond to variable, jerk and step loads.

The cleaning /replacement of fuel filters at

recommended durations improves theengine life.

FUNCTIONS OF COOLING


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FUNCTIONS OF COOLINGSYSTEM ARE

To dissipate the waste heat

generated by the engine.

Around 1/3 rd of total heat

generated is converted into

useful work.

To regulate the engine temperatureso that engine operates at optimum

temperature at all loads and

ambient conditions.


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COMPONENTS OF COOLING

SYSTEM

Radiator

Thermostat

Water Pump

Cooling Fan

Cooling Media and Pipe Lines

Oil Coolers

After Coolers

Capacity of cooling system is 161 ltrs.


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The coolant is stored in radiators.

The coolant is made to flow withwater pump once the engine isstarted. The coolant extracts theheat from cylinder block and

cylinder head, liners, throughpassages built in these.

The water is also used to cool the

intake air through turbocharger.The system need to be topped up

with premixed coolant only.


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EXHAUST SYSTEM

Around 1/3 rd of discarded heat and all theexhaust gases and unburnt fuel are givenout through exhaust system.

The back pressure in exhaust systemshould not be more than 3of Hg measuredwith a manometer close to the ex-manifold ,at maximum speed and load.

If excessive back pressure is there, lowpower and high combustion temperaturemay reduce engine life.


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PRECAUTION

The over cleaning and under cleaning of air

filters is not good for engine.

The dust and moisture in air system

reduces engine life. The engine should be run idle for 5 minutes

while switching off to allow the

turbocharger to settle because it rotates at

very high speed and sudden stopping maydamage its bearings


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ALTERNATOR

Alternator is a machine which

converts mechanical energy into

electrical energy


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COMPONENTS

MAIN STATOR

MAIN ROTOR

AVR (AUTOMATIC VOLTAGE

REGULATOR)

ROTATING RECTIFIER ASSEMBLY

EXCITER STATOR

EXCITER ROTOR

PMG STATOR

PERMANENT MAGNET ROTOR


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PMG rotor is a permanent magnet.

PMG output voltage is dependent on

speed only(approx.180V AC). AVR rectifies this voltage into DC

which is fed to exciter stator.

The three phase AC voltage of exciterrotor is given as input to rotatingrectifier assembly and this AC supplyis converted into DC.

This DC supply is given to main rotorwinding


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The three phase AC voltage of exciterrotor is given as input to rotatingrectifier assembly and this AC supply isconverted into DC.

This DC supply is given to main rotorwinding.

The AVR controls the generator outputby comparing it with set referencevoltages.

The second control is done bycontrolling speed by changing the fuelquantity.


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THANK YOU

BY:

RK SRIVASTAVA

SE/E&M

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